The present invention relates to a system for reading out three or more image recording signals from a silver halide color photographic light-sensitive material after being imagewise-exposed and subjected to processing, and processing the signals to obtain image output signals.
The most generally adopted system of the conventional color photography consists in combining a color negative film and a color print material. The color negative film in the above-mentioned system is produced by mixing three primary colors of the subtractive process with three silver halide emulsions having each a different spectral sensitivity, respectively and forming a multilayered construction of these emulsions on a support.
That is, the layered construction is composed of a unit which is sensitized by a blue component to produce a yellow dye image, a unit which is sensitized by a green component to produce a magenta dye image and a unit which is sensitized by a red component to produce a cyan dye image. In each of the constituent layers, the dye image is formed by the reaction between a developing agent, which is oxidized in the processing where the latent image forming silver halide grains are reduced to silver, and a dye precursor (a dye forming coupler). The undeveloped silver halide is removed at the fixing step, while the undesirable developed silver image is removed at the bleaching step and the fixing step that follows. A positive color print is obtained by giving an exposure to a color paper through the color negative film bearing the color image and thereafter processing the exposed paper in a manner designed for the color paper.
Recently, because of the remarkable trend of compaction of cameras, insufficiency in the sensitivity is addressed as an emerging problem of a color photographic material due to the downsizing of the built in stroboscope. In addition, since the enhancement in image quality is also important as the format is made smaller, there is a strong demand for a color photographic material which has a high sensitivity and a high image quality.
In the case of a conventional color photographic material including a color negative film, the photo-sensitive unit generally consists of three units, namely a blue-sensitive unit, a green-sensitive unit and a red-sensitive unit. Despite many continuous efforts for the enhancement in sensitivity and image quality by use of the above-mentioned construction, the objective has not been sufficiently achieved in the face of the above-mentioned small-sized stroboscope and format.
JP-A-63-95441 ("JP-A" means Published Unexamined Japanese Patent Application) discloses a method wherein a fourth light-sensitive layer, which is sensitized by white light to produce black, is formed in a position farthest from the support in addition to the conventionally adopted blue-sensitive unit, green-sensitive unit and red-sensitive unit.
By the above-described arrangement in which the white-sensitive layer has the highest sensitivity, indeed the apparent sensitivity is increased, but in practical use the high sensitivity is known to be associated with disadvantages that the sensitivity of the underlying layers drops remarkably and that any attempt to make up for the drop in the sensitivity, for example, by increasing the size of the silver halide grains increases significantly the load on the image quality and degrades the image. Other disadvantages are that, because of remarkable decrease in chroma, the above-mentioned array cannot be realized by use of a conventional printing system. Further, since the construction includes an extra layer in addition to conventional layers having spectral sensitivities, the amount of silver and the thickness of the coating naturally increase, which undesirably contradicts the recent trend for rapid processing and reduction in the quantity of replenisher.
In the case of a conventional color photographic material including a color negative film, the generally adopted arrangement of the light-sensitive units is such that a blue-sensitive unit, a green-sensitive unit and a red-sensitive unit are formed in that order from the far side of the support. This is because the light for sensitizing the material is effectively used in this arrangement and therefore this arrangement is advantageous from the viewpoint of the enhancement in sensitivity. However, it is obvious that the disadvantage of such a multilayered construction emerges in the layer nearest to the support. That is, although the blue-sensitive unit, which has thereon no coloring layer or light-scattering layer, can exhibit a high sensitivity, the green-sensitive unit, which is affected by the absorption and scattering of light by the blue-sensitive unit, suffers from the loss in sensitivity and sharpness. Likewise, the red-sensitive unit suffers from the loss due to the absorption and scattering of light by the blue-sensitive unit and the green-sensitive unit. Further, since the processing of the lower layer, namely the layer nearer to the support, is delayed, this delay undesirably causes loss in sensitivity and gradation of the lower layer.
In order to reduce the above-described load, a method has been contemplated whereby the most important layer, namely a green-sensitive unit, which has the largest contribution to the visual sensitivity, is formed in the uppermost position, i.e., the position farthest from the support. This method, however, has the problem that the sensitivity of the blue-sensitive unit, which is nearer to the support, is further remarkably decreased and the muddiness of color is excessive.
As stated above, in the case of a conventional color photographic material, which comprises a blue-sensitive unit, a green-sensitive unit and a red-sensitive unit, any attempt to increase the sensitivity of the light-sensitive unit and to improve the image quality is faced with a serious constraint, which makes it impossible to improve drastically the sensitivity and the image quality.